1. Field of the Invention
The present invention relates to a seat reclining apparatus that can recline a seatback to a seat cushion, and can lock the seatback at a desired position.
2. Description of Related Art
One of the above kinds of seat reclining apparatuses has been proposed in Japanese Patent Application Laid-open No. 2004-121508.
Seat reclining apparatuses 100 are provided on both left and right sides of a rear portion of a seat cushion (not shown), respectively. As shown in FIG. 1, the seat reclining apparatuses 100 have a pair of base brackets 101 fixed at the both left and right ends of the seat cushion, and a pair of arm brackets 102 fixed at both left and right ends of a seatback. Reclining lock mechanisms 110 are provided between the left and right base brackets 101 and the left and right arm brackets 102, respectively. Thereby, each arm bracket 102 is supported to each base bracket 101 rotatably around a center shaft 103. The center shafts 103 are connected by a connection pipe 103a, and both the center shafts 103 rotate integrally.
A spiral spring 104 is disposed outside the center shaft 103. One end of the spiral spring 104 is fixed to the base bracket 101 of the seat cushion, and the other end thereof is fixed to the arm bracket 102 of the seatback. The seatback is biased to a folded position by a spring force of the spiral spring 104.
As shown in FIG. 2 and FIG. 3, the reclining lock mechanism 110 includes a base circular case 111, an arm circular case 112, a pair of lock teeth 114, 114, a cam plate 115, and a pair of lock springs 116, 116. The circular case 111 is fixed to the base bracket 101. The arm circular case 112 is fixed to the arm bracket 102, and an inner peripheral gear 113 is formed on an inner periphery of the arm circular case 112. Each lock tooth 114, 114 is accommodated in a space formed by the both circular cases 111, 112 near the outer periphery of the space. The cam plate 115 is accommodated in the center of the space formed by both the circular cases 111, 112, and is fitted with the center shaft 103. Each lock spring 116, 116 biases the cam plate 115 in a counterclockwise direction (to a lock position side) in FIG. 2. The lock teeth 114, 114 are respectively supported swingably about fulcrums 114a, and outer peripheral gears 117, 117 are formed on outer peripheries of the lock teeth 114, 114, respectively.
A reclining operation lever 120 (shown in FIG. 1) or a folding operation lever (not shown) is attached directly or via a connection member on one portion of the center shaft 103 projected from the reclining lock mechanism 110. By operating the operation lever 120 or the like, a lock by the reclining lock mechanism 110 can be released.
In this configuration, in the reclining lock mechanism 110, the outer peripheral gears 117, 117 of the lock teeth 114, 114 are engaged with the inner peripheral gears 113, 113 of the arm circular case 112 by spring forces of the lock springs 116, 116. Thereby, the seatback is locked to the seat cushion. When a user operates the reclining operation lever 120 to rotate the center shaft 103 in a clockwise direction in FIG. 2 against the spring forces of the lock springs 116, 116, the inner peripheral gears 113, 113 and the outer peripheral gears 117, 117 are disengaged from each other so that the lock is released. When the lock is released, the seatback is folded to the folded position by the spring force of the spiral spring 104. When the user's hand is released from the reclining operation lever 120, the lock teeth 114, 114 are biased to lock positions by the spring forces of the lock springs 116, 116, but the lock teeth 114 are pressed against inner peripheral toothless portions 113a formed to be continuous to the inner peripheral gears 113, so that the seatback is not locked.
When the user pulls up the seatback against the spring force of the spiral spring 104 in order to return the seatback positioned at the folded position to a desired reclining position, the lock teeth 114, 114 are slid and moved on the inner peripheral toothless portions 113a, 113a, and the seatback is locked at a position where the inner peripheral gears 113, 113 and the outer peripheral gears 117, 117 are first engaged with each other.
When the seatback at the folded position is returned into a reclining range in this manner, the seatback is locked at a foremost position in the reclining range. Since the foremost position is set such that the seatback is put in an upright state rather than a position where seatback is ordinarily used, the user is required to operate the reclining operation lever 120 again to release the lock in the reclining lock mechanism 110, and to set the seatback to a desired reclining position. Therefore, returning the seatback positioned at the folded position to a predetermined reclining position is troublesome, and such an operation is inconvenient.
Therefore, there has been proposed a seat reclining apparatus in which a full memory unit that stores a reclining position of a seatback just before being folded is provided, so that, when the seatback positioned at a folded position is pulled up in order to return the same into a reclining range, the seatback is returned to the previous reclining position owing to the full memory unit (see Japanese Patent Application Laid-open No. 2003-516834). Such a seat reclining apparatus has also been proposed that another lock mechanism is provided in addition to a reclining lock mechanism, so that, when a seatback positioned at a folded position is pulled up to a reclining range, the seatback is returned to a predetermined reclining position by the another lock mechanism (see Japanese Patent Application Laid-open No. H8-182558).